Opened 3 months ago

Last modified 2 weeks ago

#6675 open defect

Cineform decoder distorts lower 8 pixels on 1080 video

Reported by: Garbord Owned by:
Priority: normal Component: avcodec
Version: git-master Keywords: CFHD
Cc: Blocked By:
Blocking: Reproduced by developer: yes
Analyzed by developer: no

Description

Summary of the bug:

The lower 8 pixels of 1080 height video distorts when decoding Cineform video.

This does not occur when tested against 1088 height so may be related to 1080 not being divisible by 16.

This is also visible when replayed in ffplay.

The same source file does not show the same errors when replayed in Windows Media Player, using the installable GoPro? Cineform codecs.

I've been able to see this on multiple clips. All generated from Adobe Premier Pro CC.

How to reproduce:

% ffmpeg -i input.mov -vcodec rawvideo -pix_fmt bgr24 output.mov
ffmpeg version N-87327-g18821e3 Copyright (c) 2000-2017 the FFmpeg developers
  built with gcc 7.2.0 (GCC)

Attachments (3)

ffmpeg-20170920-152131_TRUNC.log (1.1 MB) - added by Garbord 3 months ago.
Truncated log of ffmpeg console output
cineform_bw1.mov (1.8 MB) - added by cehoyos 3 months ago.
Distortions in both lower corners visible
cineform_bw2.mov (2.3 MB) - added by cehoyos 3 months ago.
If there a distortions, they are less visible

Change History (13)

Changed 3 months ago by Garbord

Truncated log of ffmpeg console output

comment:1 Changed 3 months ago by Garbord

Uploaded sample file 'Cineform_Bottom_8_Pixel_Distort_1080_YUV.mov' via VLC Uploader.

comment:2 follow-up: Changed 3 months ago by cehoyos

Unfortunately, I don't see the file there (the upload site may not work at all).
Please use datafilehost or dropbox or another file hosting site of your choice.

comment:3 in reply to: ↑ 2 Changed 3 months ago by Garbord

Replying to cehoyos:

Unfortunately, I don't see the file there (the upload site may not work at all).
Please use datafilehost or dropbox or another file hosting site of your choice.

I've uploaded the sample file here:

https://drive.google.com/open?id=0B9D-zOmjHZlrTUpCRnVldmNhTm8

I've also included a png screenshot and full version of the log.

comment:4 Changed 3 months ago by cehoyos

  • Keywords CFHD added
  • Priority changed from important to normal
  • Reproduced by developer set
  • Status changed from new to open
  • Version changed from unspecified to git-master

Thank you for the sample, I agree that it shows a possible issue with FFmpeg.

I am not sure I understand completely though:
On the file host, you provided an output file for comparison (you should not never do that unless asked, this ticket is another good example why), the png image looks very colourful here, and a little ugly on the bottom, as indicated by you.
You also uploaded a cineform file (I wonder why it is so big: Is there any difference between the first frame and the other frames, except for the timestamp?) - it looks less colourful here, actually black-and-white.
Is there any connection between the mov file and the png file you provided? Is the bug that the mov file is supposed to show colours other than black and white?

Just allow me to say that I am not 100% convinced that uploading a 1GB sample with three (or four?) different frames is super-useful.

Not a regression afaict.

Changed 3 months ago by cehoyos

Distortions in both lower corners visible

Changed 3 months ago by cehoyos

If there a distortions, they are less visible

comment:5 Changed 3 months ago by cehoyos

Sample with the most obvious distortions uploaded:
http://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket6675/

comment:6 Changed 3 months ago by Garbord

Sorry, its the first time Ive submitted a bug. I will keep samples smaller in the future.

comment:7 Changed 3 months ago by Garbord

The distortion is also visible with Cineform RGB files, though less obvious.

comment:8 Changed 3 weeks ago by kierank

comment:9 Changed 2 weeks ago by Garbord

Thanks, I'll check this against some different export files tomorrow.

Off topic I know, but now that GoPro? have open sourced their code are there any plans to integrate an encoder? I was hoping to talk to someone to get an idea of the technical challenges involved, to see if it is something to hope for in the near future. Is there a particular point of contact I can discuss this with?

comment:10 Changed 2 weeks ago by Garbord

Distortion still visible on all submitted sample files (bw1, bw2, colour).

I tested using Zerano Windows build (x64) version N-89212-ga60b2425c3 (https://ffmpeg.zeranoe.com/builds/win64/static/ffmpeg-20171123-a60b242-win64-static.zip)

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